Apparatus for helically winding strip into a lock-seamed pipe or tube

ABSTRACT

The apparatus for making helically wound, lock-seamed pipes of U.S. Pat. No. 3,122,115 is improved for use with heavier strip material by setting the axes of the pressure roller and flattening roller at an angle to the axis of the driven mandrel corresponding to the helix angle of the lock seam, by providing the strip engaging faces of the rollers with sharp edged ribs, and mounting the rollers so that the ribs bite into the strip, and by spacing the rollers apart along the seam by an angle of at least 360*.

United States Patent Siegwart [54] APPARATUS FOR HELICALLY WINDING STRIP INTO A LOCK- SEAMED PIPE OR TUBE [72] Inventor: Emil Slegwart, Michael-Blatter-Strasse 6,

6603 Sulzbach (Saar), Germany [22] Filed: Feb. 16, 1970 [21] Appl. No.: 11,376

[52] US. Cl ..72/50, 29/4773 [51] ..BZlc 37/12,B23k3l/02 [58] Field of Search ..72/49, 50; 29/4773 [56] References Cited UNITED STATES PATENTS 3,122,115 2/1964 Siegwart 922,217 5/1909 Uhri ..72/50 [451 Mar. 28, 1972 FOREIGN PATENTS OR APPLICATIONS 1,082,567 6/1960 Germany ..72/50 927,980 6/1963 England ..72/49 Primary Examiner-Charles W. Lanham Assistant Examiner-R. M. Rogers Attorney-Kelman and Herman [5 7] ABSTRACT The apparatus for. making helically wound, lock-seamed pipes of US. Pat. No. 3,122,115 is improved for use with heavier strip material by setting the axes of the pressure roller and flattening roller at an angle to the axis of the driven mandrel corresponding to the helix angle of the lock seam, by providing the strip engaging faces of the rollers with sharp edged ribs, and mounting the rollers so that the ribs bite into the strip, and by spacing the rollers apart along the seam by an angle of at least 360.

10 Claims, 4 Drawing Figures PATENTEDMAR28 m2 3,651,677

SHEET 2 [1F 2 1W3 -n I 1W1 mow Md 62mm Hes/v75 APPARATUS FOR HELICALLY WINDING STRIP INTOA LOCK-SEAMED PIPE R TUBE This invention relates to apparatus for helically winding a strip of sheet material into a lock-seamed pipe or tube, and particularly to improvements in the pipe or tube making machine disclosed in my earlier U.S. Pat. No. 3,l22,l 15.

In the earlier patent, I disclosed an apparatus mainly consisting of a mandrel, -a pressure roller and a flattening or folding roller, the mandrel being driven by a motor, and the rollers being turned by engagement with the strip. The longitudinal edges of the strip, prior to winding on the mandrel in a helix and engagement with the pressure roller, are bent out of the plane of the central strip portion, one edge being folded over to form a U-shaped channel in which the other edge on a preceding turn of the helix is received.

The pressure roller provides guidance for the edge portions to engage the same and shifts the helically wound strip axially on the mandrel. The lock seam partly formed by the pressure roller and obliquely projecting from the pipe or tube formed by the central portion of the strip is then flattened against the cylindrical outer pipe or tube wall by the flattening or folding roller.

While the aforedescribed apparatus, more fully described in the patent, has been used successfully for several years, it is limited in the thickness or rigidity of the strip material that can be made into tubes if a precisely defined cross section is required. When relatively stiff or heavy sheet metal strip is used on the known device, the strip is not wound tight enough about the mandrel.

The primary object of the instant invention is an improvement in the earlier apparatus which permits the same to handle heavier or more rigid strip stock and yet to make pipes and tubes of uniform, predictable dimensions and regular shape.

With this object in view, the invention provides at least one of the two rollers, but preferably both, with sharp edged ribs in their sheet-engaging circumferential faces. The rollers are mounted so close to the mandrel that the ribs bite into the strip, thereby preventing axial slippage of the strip material on the mandrel. Additionally, the two rollers should be mounted spaced along the helix of the lock seam by an angle of at least 360 to increase the capstan action of the mandrel on the strip,

and to thereby tightly wind the strip about the mandrel face in precisely conforming engagement. Additionally, the axes of rotation of the two rollers should be tilted relative to the mandrel axis at an angle corresponding to the inclination of the helix.

Other features, additional objects and many of the attendant advantages of this invention will readily become apparent as the same becomes better understood by reference to the following detailed description when considered in connection with the appended drawing in which:

FIG. 1 shows a pipe or tube winding apparatus of the invention in fragmentary side elevation together with portions of a pipe or tube being wound on the apparatus;

FlGS. 2 and 3 illustrate portions of the device of FIG. 1 on a larger scale; and

F [6. 4 shows a portion of the pipe or tube of FIG. 1 in an intermediate stage of its construction together with the mandrel of the apparatus of FIG. 1.

Referring now to the drawing in detail, there is seen an apparatus similar in many respects to the tube or pipe making machine of the aforementioned patent. A sheet metal strip 1 is fed to a motor-driven mandrel 2 in a direction which is obliquely inclined to the mandrel axis, at such an angle that the strip is wound on the mandrel in a helix, and the trailing or left edge portion 3 of each turn of the strip, as viewed in all Figures of the drawing, in engaged by the right or leading edge portion 4 of the next turn, as the spirally wound strip slides axially over the mandrel 2 from the left to the right.

When fed to the mandrel 2, the strip 1 is already pre-folded so that the left edge portion 3 is bent out of the plane of the central strip portion through an angle A of about 120 (FIG. 2). The right edge portion 4 is doubled over into an approximate U-shape and offset from the central strip portion by an I angle B of about 60, the dimensions of the edge portions being such that the edge portion 3 fits into the bight of the edge portion 4.

The edge portion 3 is engaged in the edge portion 4 of a subsequent tum while the two edge portions enter a circumferential groove 6 of a pressure roller 5. The groove has a conical left sidewall 7, a right sidewall which is radial relative to the axis of rotation of the roller, and an axially short, cylindrical bottom wall, the inclination of the conical sidewall 7 being selected to match the trailing face of the edge portion 4. The two generally cylindrical faces 8,9 of the roller 5 on either side of the groove 6 have a multitude of shallow circumferential grooves which are separated by sharp-edged circular ribs 10.

The roller 5 is journaled in the stationary frame of the machine at such a distance from the mandrel 2 that the sharp edges or ridges of the ribs 10 bite into the metal strip 1. While the axis of rotation of the roller 5 has been shown in FIG. 1 to be parallel to that of the mandrel for greater clarity of the drawing, the two axes are actually offset at an angle equal to the inclination of the helical seam.

The faces 8,9 hold the sheet metal strip 1 in conforming engagement with the mandrel 2 during engagement of the edge portions 3,4, and the ribs 10 cause the partly assembled tube or pipe to move axially along the mandrel at a rate precisely commensurate with the inclination of the seam. When released from the pressure roller 5, the interengaged edges 3,4 tend to approach the cylindrical outer face of the pipe or tube formed by the original central strip portion between consecutive turns of the seam.

A flattening roller 11 offset two and one-half turns from the roller 5 along the folded seam bends the folded edge portions flat against the body of the pipe or tube. Because the angle of wrap of the strip 1 on the mandrel 2 between the two rollers 5,1] is greater than 360, the mandrel can exert strong pulling forces on the strip in the manner of a capstan, the pulling force increasing exponentially with the angle of wrap. Because of the magnitude of the pulling force, the spiral-wound strip tightly envelops the mandrel 2 and the internal cross section of the finished pipe or tube is precisely determined.

As long as the engaged edge portions 3,4 are still oblique relative to the mandrel axis, consecutive turns of the strip 1 may shift slightly relative to each other to adjust to the mandrel circumference. When the seam is flattened and the edge portions 3,4 are practically parallel to the mandrel axis, no further changes in the size or configuration of the tube can occur on the winding machine. The axial portion of the mandrel beyond the flattening roller 11 tapers conically at an angle too small to permit realistic representation in the drawing, but sufficient to reduce friction between the wound pipe or tube and the tapering mandrel portion to an insignificant value. v The flattening roller 11 has an axially central, circumferential groove 13 which receives the seam of engaged edge portions 3,4 while the mandrel 2 and the roller 1 1 rotate about respective, angularly offset axes in a manner described above with reference to the roller 5, but not shown in the drawing. The basically cylindrical surfaces of the roller 11 on either side of the groove 13 have sharp-edged ribs 12, and the roller is journaled in the machine frame close enough to the mandrel 2 that the ribs 12 bite into the strip 1. Similar ribs may also be provided on the recessed cylindrical bottom wall of the groove 13 for handling particularly'heavy strip material. The groove 13 is shallow enough to press thelock seam against the outer wall of the pipe or tube, to reduce the depth of the helical recess in the inner pipe or tube wall by cold flow of the metal and tightly to clamp the edge portion 3 between the two layers of the folded edge portion 4. The seam is axially confined between the conical sidewalls 16 of the groove 13.

The forces exerted by the rollers 5 and 11 on the engaged edge portions 3,4 are indicated by arrows 14,15 in FIG. 4. Because the strip 1 is initially flat, bending of the strip over the surface of the mandrel 2 by the roller 5 generates stresses in the edge portions in the direction of the arrow 14. These stresses tend to bend the engaged edge portions toward the outer pipe or tube wall. The forces transmitted by the roller 11 to the engaged edge portions are mainly radial, as indicated by the arrow 15. The axial forces necessary for shifting the wound pipe or tube on the tightly engaged mandrel 2 are transmitted by the ribs 10,12 by the conical wall 7 of the groove 6, and by the left conical wall 16 of the roller 1 1.

If it is desired to produce a pipe or tube whose inner wall is perfectly smooth, a wire or strip of a malleable metal, such as aluminum, may be fed to the mandrel jointly with the strip 1 to fill the helical recess on the inner wall at the seam of the edge portions 3,4. The malleable wire or strip may be partly anchored between the edge portions 3,4 in the bight of the edge portion 4.

What is claimed is:

1. In an apparatus for making a pipe or tube having a helical lock seani from an elongated strip of sheet material, the apparatus having a mandrel driven for rotation about a first axis and adapted to have said strip wound thereon in a helix about said axis, a pressure roller, mounting means mounting said pressure roller adjacent said mandrel for rotation about a second axis in a position fixed relative to said first axis, said roller having a face about said second axis shaped and positioned for engagement with a lock seam formed by interengaged respective edge portions of consecutive turns of the helically wound strip, a flattening roller, additional mounting means mounting said flattening roller adjacent said mandrel for rotation about a third axis in a position fixed relative to said first axis and offset relative to the position of said pressure roller along said helix for flattening said seam against the outer wall of said pipe or tube, the improvement which comprises:

a. a plurality of sharp-edged ribs extending on one of said rollers about the axis of rotation of said one roller;

b. the mounting means associated with said one roller including means for holding said ribs in engagement with said strip with a force sufficient to cause the ribs to bite into said strip during rotation of said one roller.

2. In an apparatus as set forth in claim 1, a plurality of sharp-edged ribs extending on the other one of said rollers about the axis of rotation of said other roller, the mounting means associated with said other roller including means for holding the ribs of said other roller in engagement with said strip with a force sufiicient to cause the last-mentioned ribs to bite into said strip.

3. In an apparatus as set forth in claim 2, the ribs on said pressure roller constituting a plurality of pairs of ribs, the ribs of each pair defining therebetween a shallow groove, and said ribs on the pressure roller constituting two groups of ribs separated by a circumferential groove in said roller deeper than said shallow grooves and adapted to receive said seam.

4. In an apparatus as set forth in claim 3, said pressure roller having a substantially conical face about said second axis in said deeper groove, said conical face being directed axially toward the position of said flattening roller.

5. In an apparatus as set forth in claim 2, said ribs of the flattening roller extending in a common cylindrical surface about said third axis, said flattening roller having a substantially cylindrical, recessed face about said third axis of a diameter smaller than the diameter of said common surface and adapted to engage said seam during the flattening of the same,

said flattening roller including additional sharp-edged ribs about said third axis on said recessed face.

6. In an apparatus as set forth in claim 2, the position of said flattening roller being offset relative to the position of said pressure roller along said helix by an angle of at least 360.

7. In an apparatus as set forth in claim 2, said second axis and said third axis being each angularly offset from said first axis at an angle equal to the inclination of said helix.

8. In an apparatus as set forth in claim 2, an axial portion of said mandrel extending from the position of said flattening roller in a direction away from the position of said pressure roller and tapering in said direction.

9. In an apparatus as set forth in claim 1, the sharp edges of said ribs being located substantially in a common cylindrical surface about said axis of rotation and defining therebetween a plurality of grooves.

10. In an apparatus as set forth in claim 2, the sharp edges of the ribs on each of said rollers being located substantially in a common cylindrical surface about the axis of rotation of the corresponding roller and defining therebetween a plurality of grooves on said roller. 

1. In an apparatus for making a pipe or tube having a helical lock seam from an elongated strip of sheet material, the apparatus having a mandrel driven for rotation about a first axis and adapted to have said strip wound thereon in a helix about said axis, a pressure roller, mounting means mounting said pressure roller adjacent said mandrel for rotation about a second axis in a position fixed relative to said first axis, said roller having a face about said second axis shaped and positioned for engagement with a lock seam formed by interengaged respective edge portions of consecutive turns of the helically wound strip, a flattening roller, additional mounting means mounting said flattening roller adjacent said mandrel for rotation about a third axis in a position fixed relative to said first axis and offset relative to the position of said pressure roller along said helix for flattening said seam against the outer wall of said pipe or tube, the improvement which comprises: a. a plurality of sharp-edged ribs extending on one of said rollers about the axis of rotation of said one roller; b. the mounting means associated with said one roller including means for holding said ribs in engagement with said strip with a force sufficient to cause the ribs to bite into said strip during rotation of said one roller.
 2. In an apparatus as set forth in claim 1, a plurality of sharp-edged ribs extending on the other one of said rollers about the axis of rotation of said other roller, the mounting means associated with said other roller incluDing means for holding the ribs of said other roller in engagement with said strip with a force sufficient to cause the last-mentioned ribs to bite into said strip.
 3. In an apparatus as set forth in claim 2, the ribs on said pressure roller constituting a plurality of pairs of ribs, the ribs of each pair defining therebetween a shallow groove, and said ribs on the pressure roller constituting two groups of ribs separated by a circumferential groove in said roller deeper than said shallow grooves and adapted to receive said seam.
 4. In an apparatus as set forth in claim 3, said pressure roller having a substantially conical face about said second axis in said deeper groove, said conical face being directed axially toward the position of said flattening roller.
 5. In an apparatus as set forth in claim 2, said ribs of the flattening roller extending in a common cylindrical surface about said third axis, said flattening roller having a substantially cylindrical, recessed face about said third axis of a diameter smaller than the diameter of said common surface and adapted to engage said seam during the flattening of the same, said flattening roller including additional sharp-edged ribs about said third axis on said recessed face.
 6. In an apparatus as set forth in claim 2, the position of said flattening roller being offset relative to the position of said pressure roller along said helix by an angle of at least 360*.
 7. In an apparatus as set forth in claim 2, said second axis and said third axis being each angularly offset from said first axis at an angle equal to the inclination of said helix.
 8. In an apparatus as set forth in claim 2, an axial portion of said mandrel extending from the position of said flattening roller in a direction away from the position of said pressure roller and tapering in said direction.
 9. In an apparatus as set forth in claim 1, the sharp edges of said ribs being located substantially in a common cylindrical surface about said axis of rotation and defining therebetween a plurality of grooves.
 10. In an apparatus as set forth in claim 2, the sharp edges of the ribs on each of said rollers being located substantially in a common cylindrical surface about the axis of rotation of the corresponding roller and defining therebetween a plurality of grooves on said roller. 